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71.
Shiyao Li Chuntian Wu Huiwen Cheng Hengqiang Li Beilu Li 《Reaction Kinetics and Catalysis Letters》1998,65(2):293-300
The high-temperature durability of cordierite honeycomb Rh-free three-way catalysts (TWC) containing additives has been studied
by calcining catalysts at various temperatures in the interval of 600≈1100°C. The three-way performances of these catalysts
were evaluated for the reaction of carbon monoxide(CO), hydrocarbon(HC) and nitrogen oxides(NOx) at given conditions by using
a fixed bed reactor. The results show that after Rh-free TWC are thermally aged in air at 1100°C for 5h and 950°C for 104
h, the TWC still have better three-way activity compared with Rh-containing TWC. 相似文献
72.
73.
固体磷酸催化剂的活性相 总被引:8,自引:0,他引:8
研究了固体磷酸催化剂活性与其自由磷酸聚合态及磷酸硅晶型的关系,指出高活性磷酸催化剂应具备的条件,即自由磷酸中应为正磷酸和焦磷酸的混合物,结合态磷应具有“C”晶型。 相似文献
74.
Sadahito Aoshima Tomohide Yoshida Arihiro Kanazawa Shokyoku Kanaoka 《Journal of polymer science. Part A, Polymer chemistry》2007,45(10):1801-1813
Our recent extensive research on Lewis acid catalysts with a weak base for the cationic polymerization of vinyl ethers led to unprecedented living reaction systems: fast living polymerization within 1–3 s; a wide choice of metal halides containing Al, Sn, Fe, Ti, Zr, Hf, Zn, Ga, In, Si, Ge, and Bi; and heterogeneously catalyzed living polymerization with Fe2O3. The use of added bases for the stabilization of the propagating carbocation and the appropriate selection of Lewis acid catalysts were crucial to the success of such new types of living polymerizations. In addition, the base‐stabilized living polymerization allowed the quantitative synthesis of star‐shaped polymers with a narrow molecular weight distribution via polymer‐linking reactions and the precision synthesis and self‐assembly of stimuli‐responsive block copolymers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1801–1813, 2007. 相似文献
75.
CeO2-ZrO2-Y2O3对Pt-Rh型三效催化剂性能的影响 总被引:4,自引:0,他引:4
采用共沉淀法技术制备了Ce0.35Zr0.55Y0.10固溶体,并对其进行了比表面积、储氧量的测试和XRD的表征.将其用于低贵金属Pt-Rh型三效催化剂的制备,考察了CeO2-ZrO2-Y2O3对三效催化剂性能的影响.结果表明,Ce0.35Zr0.55Y0.10具有与Ce0.50Zr0.50O2相似的立方结构和相近的储氧量,经高温(1000 ℃)后仍能保持较大的比表面积(38.66 m2·g-1).和含Ce0.50Zr0.50O2的三效催化剂相比,含CeO2-ZrO2-Y2O3的三效催化剂经高温老化后,C3H8,CO,NO仍具有较高的转化率和较低的起燃温度. 相似文献
76.
The reaction of diethyl 3-ethoxycarbonyl-2-methyl-2-propenylphosphonate (1a) with 3-methylbutanal (2) in heterogeneous MOH (solid)-benzene systems in the presence of 5–10 mol.% of benzyltriethylammonium chloride (BTEAC) gives the reaction product (3) with a higher, for M=K, or lower, for M=Li, ratio of 2E,4E and 2Z,4E-stereoisomers than that observed in the absence of BTEAC. Tetrabutylammonium bromide (TBAB) as a catalyst of the reaction1a + 2 3 in the system KOH (solid)-wet benzene leads to a higher [2E,4E-3][2Z,4E-3] ratio than BTEAC; this ratio grows from 4456 without TBAB to 8020 at 100 mol.% of TBAB. In the latter case the stereochemical outcome of the reaction is similar to that obtained when tetrabutylammonium hydroxide in dry benzene is used as the deprotonating agent. The corresponding diisopropyl phosphonate (1b) and 3,7-dimethyloctanal (4a) interact in the system KOH (solid)-wet benzene-TBAB to give hydroprene (5) containing 88 % of the 2E,4E-isomer (5a) while in the case of 1 equiv. of [(n-Bu4)N]OH in dry benzene the content of5a is 92 %. Diisopropyl 3-isopropoxycarbonyl-2-methyl-2-propenylphosphonate (1c) and 7-methoxy-3,7-dimethyloctanal (4b) under either of these conditions afford methoprene (6) containing 93 % of the 2E,4E-isomer.Part 6, see ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1094–1098, June, 1993. 相似文献
77.
The combination of ethyl diazoacetate with aryl aldehydes in the presence of copper(I) or rhodium(II) catalysts results in
the formation of 1,3-dioxolane products in moderate to good yields. These reactions occur through a pathway that involves
ylide intermediates. Catalyst-dependent diastereocontrol is observed and suggests that metal-associated ylides are involved
in the product-determining step. The influence of aryl aldehyde substituents has been determined.
Current address.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 961–965, May, 1998. 相似文献
78.
Toshio Koizumi Jun Sakamoto Yasuhiko Gondo Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2002,40(14):2487-2494
The palladium(0)‐catalyzed polyaddition of bifunctional vinyloxiranes [1,4‐bis(2‐vinylepoxyethyl)benzene ( 1a ) and 1,4‐bis(1‐methyl‐2‐vinylepoxyethyl)benzene ( 1b )] with 1,3‐dicarbonyl compounds [methyl acetoacetate ( 4 ), dimethyl malonate ( 6 ), and Meldrum's acid ( 8 )] was investigated under various conditions. The polyaddition of 1 with 4 was carried out in tetrahydrofuran with phosphine ligands such as PPh3 and 1,2‐bis(diphenylphosphino)ethane (dppe). Polymers having hydroxy, ketone, and ester groups in the side groups ( 5 ) were obtained in good yields despite the kinds of ligands employed. The number‐average molecular weight value of 5b was higher than that of 5a . The polyaddition of 1b and 6 was affected by the kinds of ligands employed. The corresponding polymer 7b was not obtained when PPh3 and 1,2‐bis(diphenylphosphino)ferrocene were used. The polyaddition was carried out with dppe as the ligand and gave polymer 7b in a good yield. The molecular weight of the polymer obtained from 1b and 8 was much higher than those of polymers 5b and 7b . The polyaddition with Pd2(dba)3 · CHCl3/dppe as a catalyst (where dba is dibenzylideneacetone) produced polymer 9b in a 92% yield (number‐average molecular weight = 45,600). The stereochemistries of all the obtained polymers were confirmed as an E configuration by the coupling constant of the vinyl proton. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2487–2494, 2002 相似文献
79.
The texture of Cr2O3-K2O/Al2O3catalysts containing oxides of rare earth elements (REE) was studied. The catalysts are used for the synthesis of 2-methylthiophene by the reaction of H2S with n-pentane or piperilene. The heterocyclization of n-pentane is a consecutive reaction involving a step of dehydrogenation of initial hydrocarbon. At this step the texture of the catalyst affects the yield of 2-methylthiophene. The yield of 2-methylthiophene obtained from piperilene and I2S is independent of the catalyst texture. 相似文献
80.
Zhuang Hong Cheng Tiexin Bi Yingli Zhou Guangdong Zhen Kaiji 《Reaction Kinetics and Catalysis Letters》2004,81(1):13-20
Factors (reaction temperature, reaction time, flow rate of oxygen, amount of catalyst, etc.) influencing the catalytic properties of Co3O4/SiO2catalyst in the oxidation octadecan-1-ol to octadecanoic acid were investigated. The catalysts were characterized by means of XRD, FT-IR and N2-adsorption. The experimental results indicate that under the optimal condition the selectivity to octadecanoic acid reached 97.5 % over 5 % Co3O4/SiO2 catalyst.This revised version was published online in December 2005 with corrections to the Cover Date. 相似文献